In a bowl, combine avocado oil, lemon juice, lemon zest, garlic powder, dried rosemary, dried thyme, dried oregano, salt, and pepper.
Place chicken in a shallow dish and pour the mixture over them, turning to coat evenly.
Cover and refrigerate the chicken for at least 20 minutes or up to 2 hours. If you're short on time, you can cook it immediately. Let the chicken sit at room temperature for 10–15 minutes before grilling so it cooks evenly.
Heat a grill pan over medium-high heat until hot.
Remove chicken from marinade, letting excess drip off.
Place chicken on the hot grill pan and cook for 5-7 minutes per side until grill marks appear and internal temperature reaches165°F.
Remove chicken to a plate and let rest for 3 minutes.
Garnish with lemon slices, if desired.